Reformer-gas-based reduction process with decarbonization of the fuel gas for the reformer

ABSTRACT

In a process and apparatus for the reduction of metal oxides to form metalized material by contact with hot reducing gas, which is produced at least partially by catalytic reformation of a mixture of—a gas containing carbon dioxide (CO 2 ) and/or steam (H 2 O) with—gaseous hydrocarbons, the fuel gas for burners which provide the heat for the endothermal reformation processes which take place during the reformation is obtained at least partially from a partial quantity of the top gas produced during the reduction of metal oxides to form metalized material, wherein this partial quantity of the top gas, before it is used as a component of the fuel gas, is firstly subjected to dedusting and then to a CO conversion reaction, and the conversion gas obtained during the CO conversion reaction is subjected to CO 2  removal after cooling.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application of InternationalApplication No. PCT/EP2010/060130 filed Jul. 14, 2010, which designatesthe United States of America, and claims priority to Austrian PatentApplication No. A 1217/2009 filed Jul. 31, 2009. The contents of whichare hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a process for the reduction of metaloxides to form metalized material by contact with hot reducing gas,which is produced at least partially by catalytic reformation of amixture of

-   -   a gas containing carbon dioxide (CO₂) and/or steam (H₂O) with    -   gaseous hydrocarbons,

wherein the fuel gas for burners which provide the heat for theendothermal reformation processes which take place during thereformation is obtained at least partially from a partial quantity ofthe top gas produced during the reduction of metal oxides to formmetalized material, wherein this partial quantity of the top gas, beforeit is used as a component of the fuel gas, is firstly subjected todedusting and then to a CO conversion reaction, and the conversion gasobtained during the CO conversion reaction is subjected to CO₂ removalafter cooling. Furthermore, the present invention relates to anapparatus for carrying out the process.

BACKGROUND

By way of example, FIG. 1 of WO2006135984 describes a process for thereduction of metal oxides to form metalized material by contact with hotreducing gas, which is produced by catalytic reformation of a mixture ofnatural gas with the top gas taken from the reduction unit, wherein thefuel gas for burners which provide the heat for the endothermalreformation processes which take place during the reformation isobtained from a partial quantity of the top gas produced during thereduction of metal oxides to form metalized material and from naturalgas. Owing to ever more stringent statutory environmental regulations,it is desirable to separate CO₂ in order to produce a concentrated CO₂flow from the off-gases produced during the processes, with thepossibility of subsequent sequestration of the CO₂ flow, before theoff-gases treated in this way are released into the environment. In thecase of a process as shown in W02006135984, the fuel gas for thereformer is combusted with air as the oxygen source, for which reasonthe combustion off-gas contains a large quantity of nitrogen.Correspondingly, downstream plants for removing CO₂ from the combustionoff-gas have to have large dimensions. Additionally, substantially onlychemical absorption processes are suitable for removing CO₂ from thecombustion off-gas, and these are distinguished by a large plant sizeand a high consumption of energy, which is supplied, for example, usingsteam.

SUMMARY

According to various embodiments, a process can be provided which makesit possible to avoid the presence of CO₂ in the combustion off-gas usingsmaller plants—with correspondingly lower levels of consumption—andmakes other CO₂ removal processes possible, and also an apparatus forcarrying out the process.

According to an embodiment, in a process for the reduction of metaloxides to form metalized material by contact with hot reducing gas, thereducing gas is produced at least partially by catalytic reformation ofa mixture of—a gas containing carbon dioxide (CO2) and/or steam (H2O)with—gaseous hydrocarbons, wherein the heat for the endothermalreformation processes which take place during the reformation isprovided at least partially by the combustion of a fuel gas, and thecombustion off-gas produced in the process is drawn off, wherein thefuel gas is obtained at least partially from a partial quantity of thetop gas produced during the reduction of metal oxides to form metalizedmaterial, and wherein the partial quantity of the top gas, from whichthe fuel gas is obtained, is firstly subjected to dedusting and then toa CO conversion reaction, and the conversion gas obtained during the COconversion reaction is subjected to CO2 removal after cooling, and theCO2-depleted conversion gas produced in the process is used at least asa component of the fuel gas.

According to a further embodiment, the gas containing carbon dioxide(CO2) and/or steam (H2O) can be top gas from the process for thereduction of metal oxides. According to a further embodiment, the gascontaining carbon dioxide (CO2) and/or steam (H2O) can be export gasfrom a smelting reduction process or syngas from a coal gasificationprocess. According to a further embodiment, gaseous hydrocarbons can beadmixed to the CO2-depleted conversion gas in order to obtain fuel gas.According to a further embodiment, the dedusting may take place in dryform or in wet form.

According to another embodiment, an apparatus for carrying out theprocess as described above, may have a reduction unit for the reductionof metal oxides to form metalized material, and a reformer for carryingout catalytic reformation of a mixture of—a gas containing carbondioxide (CO2) and/or steam (H2O) with—gaseous hydrocarbons, wherein thereformer is provided with a mixture supply line for supplying themixture, and wherein the reformer is provided with burners, which areconnected to an oxygen supply line, for providing heat by the combustionof fuel gas, having a drawing-off line for drawing off combustionoff-gas from the reformer, having a reducing gas supply line for hotreducing gas from the reformer into the reduction unit, having adischarge line for discharging top gas from the reduction unit, whereinthe burners are connected to the discharge line via a connection linewhich branches off from the discharge line, and wherein a dedustingapparatus is present at least in the discharge line between thereduction unit and the connection line which branches off from it, or inthe connection line, wherein a CO conversion reactor, a gas coolingapparatus and a CO2 removal apparatus are present in succession, as seenfrom the discharge line, in the connection line, between the dedustingdevice which may be present and the burners.

According to a further embodiment of the apparatus, a hydrocarbon feedline for gaseous hydrocarbons may issue into the connection line.According to a further embodiment of the apparatus, the hydrocarbon feedline for gaseous hydrocarbons may issue into the connection linedownstream from the CO2 removal apparatus, as seen from the dischargeline. According to a further embodiment of the apparatus, the dedustingapparatus can be a dry-dedusting apparatus. According to a furtherembodiment of the apparatus, the dedusting apparatus can be awet-dedusting apparatus. According to a further embodiment of theapparatus, a gas heating apparatus can be present in the connection linebetween the wet-dedusting apparatus and the CO conversion reactor.According to a further embodiment of the apparatus, the reduction unitcan be a fluidized bed cascade. According to a further embodiment of theapparatus, the reduction unit can be a fixed-bed reduction shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

In the text which follows, the various embodiments are explained in moredetail with reference to a plurality of schematic figures.

FIG. 1 shows an apparatus according to various embodiments with wetdedusting.

FIG. 2 shows an apparatus according to various embodiments with combinedwet and dry dedusting.

FIG. 3 shows an apparatus according to various embodiments purely withdry dedusting and cooling of the top gas.

FIG. 4 shows a process corresponding to FIG. 2, where the gas containingcarbon dioxide (CO₂) and/or steam (H₂0) originates from a sourcedifferent to that in FIG. 2.

DETAILED DESCRIPTION

As stated above, according to various embodiments, in a process for thereduction of metal oxides to form metalized material by contact with hotreducing gas, the reducing gas is produced at least partially bycatalytic reformation of a mixture of

-   -   a gas containing carbon dioxide (CO₂) and/or steam (H₂O) with    -   gaseous hydrocarbons,

wherein the heat for the endothermal reformation processes which takeplace during the reformation is provided at least partially by thecombustion of a fuel gas, and the combustion off-gas produced in theprocess is drawn off, wherein the fuel gas is obtained at leastpartially from a partial quantity of the top gas produced during thereduction of metal oxides to form metalized material, characterized inthat the partial quantity of the top gas, from which the fuel gas isobtained, is firstly subjected to dedusting and then to a CO conversionreaction, and the conversion gas obtained during the CO conversionreaction is subjected to CO₂ removal after cooling, and the CO₂-depletedconversion gas produced in the process is used at least as a componentof the fuel gas.

The metal oxides are preferably iron oxides. However, according to theRichardson-Jeffes diagram, nickel, copper, lead and cobalt canfurthermore also be reduced, for example.

The reducing gas is produced at least partially by catalytic reformationof a mixture of

-   -   a gas containing carbon dioxide CO₂ and/or steam H₂O with    -   gaseous hydrocarbons.

This reformation takes place by at least partial conversion of thegaseous hydrocarbons with H₂O and CO₂ to form hydrogen (H₂) and carbonmonoxide (CO). The substances H₂O and/or CO₂ required for thereformation can be added to the mixture for reformation in each caseindividually or together, and/or the H₂O and/or CO₂ present in the gascontaining carbon dioxide CO₂ and/or steam H₂O is used. It is preferableto add at least H₂O—as steam—to the mixture.

Gaseous hydrocarbons are to be understood as meaning, for example,natural gas, methane, propane, syngas from coal gasification or cokefurnace gas. The term “gaseous hydrocarbons” includes both thepossibility that only one compound, for example pure propane, ispresent, and also the possibility that a mixture of a plurality ofcompounds is present, for example a mixture of propane and methane.

The gas containing carbon dioxide CO₂ and/or steam H₂O is, for example,top gas from the process according to various embodiments for thereduction of metal oxides. In this case, top gas is to be understood asmeaning the gas which is discharged from the reduction unit in which themetal oxides are reduced to form metalized material. Before thereformation, the top gas may also be cleaned, for example by theseparation of dust and/or water carried along.

The gas containing carbon dioxide CO₂ and/or steam H₂O can also be, forexample, export gas from a different process for the reduction of metaloxides, for example a smelting reduction process, or syngas from a coalgasification process, for example a Lurgi fixed-bed gasifier or Siemensentrained-flow gasifier.

With preference, the gas is top gas from the process according tovarious embodiments for the reduction of metal oxides.

Table 1 shows a typical composition of top gas from a direct reductionprocess:

TABLE 1 Typical gas composition of DR top gas Top gas composition aftergas cleaning CO [% by volume] 20-25 CO₂ [% by volume] 15-20 H₂ [% byvolume] 40-46 H₂O [% by volume]  0-18 CH₄ [% by volume] 2-4 N₂ [% byvolume] 1-2

In the gas containing carbon dioxide CO₂ and/or steam H₂O, the lowerlimit for the carbon dioxide CO₂ content is 0% by volume, preferably 5%by volume, particularly preferably 15% by volume, and the upper limitfor the carbon dioxide CO₂ content is 25% by volume, preferably 30% byvolume, particularly preferably 40% by volume.

In the gas containing carbon dioxide CO₂ and/or steam H₂O, the lowerlimit for the steam H₂O content is 0% by volume, preferably 10% byvolume, and the upper limit for the steam H₂O content is 20% by volume,preferably 55% by volume.

The catalytic reformation produces a reducing gas which containsprincipally H₂ and CO as reducing constituents. It is known that suchreformation involves an endothermal reaction, and for this reason heatis supplied to the reformer, for example by the combustion of fuel gaswith oxygen, in burners associated with the reformer. By way of example,the oxygen is provided by the supply of air, the supply of a differentoxygen-containing gas mixture or the supply of technically pure oxygen.

In order to increase the efficiency of the process as a whole, the fuelgas is obtained at least partially from a partial quantity of the topgas produced during the reduction of metal oxides to form metalizedmaterial. This top gas also contains combustible constituents, forexample CO and H₂, which are used in the burners of the reformer toproduce the heat required for the reformation.

According to various embodiments, the partial quantity of the top gas,from which the fuel gas is obtained, is subjected to a CO conversionreaction (also referred to as a CO shift reaction or water gas shiftreaction). This known reaction serves to simultaneously reduce the COcontent in the top gas and increase the H₂ content, with CO₂ beingformed simultaneously.

CO+H₂O

CO₂+H₂ΔH⁰ _(R 298)=−41.2 kJ/mol

After the CO conversion reaction, according to various embodiments theCO₂ and H₂O contents are cooled and removed in a CO₂ removal plant,before they are used as fuel gas. Here, the CO₂ is already efficientlyseparated before the combustion. Accordingly, the effort required toremove CO₂ from the combustion off-gas can be reduced.

By virtue of these measures, a fuel gas containing principally hydrogenH₂ as combustible component is supplied to the burners of the reformer.This has the advantage that less CO₂ is produced as a result ofcombustion in the burners, since the proportion of CO components whichgenerate CO₂ during the combustion in the fuel gas is low.

The CO conversion reaction preferably takes place on the basis ofhigh-temperature or crude-gas conversion processes, since neither ofthese processes is overly sensitive to the presence of hydrogen sulfide(H₂S) in the gas flow to be treated. The CO conversion reaction is anexothermal reaction, but can also be an isothermal reaction and in thiscase can be used, for example, for producing steam. Depending on the COconversion process, an inlet temperature of 160-450° C., preferably300-450° C. in the case of a high-temperature CO conversion process, hasto be complied with for operation of the CO conversion reactor. If thetop gas is washed when wet before the CO conversion reaction, it isnecessary to carry out heating to such temperatures after the wet washowing to the associated drop in temperature. If the top gas is dedustedwhen dry before the CO conversion reaction, the temperature of the topgas can equally be employed for the subsequent CO conversion reaction.

According to various embodiments, the CO conversion reaction is followedby cooling and separation of CO₂ and H₂O from the flow of the conversiongas obtained during the CO conversion reaction. Since the flow of theconversion gas contains only a small amount of nitrogen compared to thecombustion off-gas, and the CO₂ is accordingly present in moreconcentrated form than in the combustion off-gas, and because the CO₂ isremoved before the combustion, the gas volume to be subjected to CO₂removal is less than in the case of the removal of CO₂ from combustionoff-gas. Accordingly, the removal is less complex.

CO₂ does not make a contribution to the calorific value of the fuel gas.In conventional processes for the use of top gas—which already containsCO₂ after the reduction of the metal oxides—in the fuel gas, it istherefore often necessary to admix gaseous hydrocarbons, for examplenatural gas, in order to increase the calorific value of the fuel gas toan extent required to achieve the required flame temperature in thereformer. Since, according to various embodiments, the CO₂ is removedbefore the combustion—and owing to the associated increase in thecalorific value of the fuel gas—it is generally possible to dispensewith such an admixture of gaseous hydrocarbons. It is of course alsopossible to admix gaseous hydrocarbons if required.

Such an admixture can be carried out such that gaseous hydrocarbons areadmixed to the CO₂-depleted conversion gas in order to produce fuel gas.

If nothing is admixed to the CO₂-depleted conversion gas before it isused as fuel gas, the CO₂-depleted conversion gas is the fuel gas. Ifsomething is admixed to the CO₂-depleted conversion gas, for examplegaseous hydrocarbons, this is a component of the fuel gas.

A further advantage of various embodiments is that the combustionoff-gas can be used extremely effectively as seal gas after possibleseparation of water. A seal gas is defined as a noncombustible and inertgas for sealing off the outlet of process gas and for providing an inertatmosphere over a material. Seal gas is used, for example, for thecharging of raw materials and in the shaft discharge of a reductionshaft, or for hot conveyors. The gas obtained after possible separationof water from the combustion off-gas in the process according to variousembodiments contains, as main constituent, nitrogen and barely any CO₂.By contrast, combustion off-gas produced according to a process as shownin FIG. 1 of WO2006135984 contains 18 to 20% by volume CO₂, which canlead to reoxidation and thus to product impairment on contact withproduct from the reduction process, for example hot DRI (direct reducediron), for example in the shaft discharge of a reduction shaft or in hotconveyors. When the combustion off-gas produced according to variousembodiments is used as seal gas, a risk of this nature does not arise.

Owing to the high temperature of the conversion gas produced, it isnecessary in the process according to various embodiments for theconversion gas to be cooled before the CO₂ removal in order to obtain atemperature required for the CO₂ removal, preferably from 30-60° C.Steam which is introduced during the conversion reaction, but isunconverted, is preferably also removed from the conversion gas bycondensation.

Furthermore, it is necessary to dedust the partial quantity of the topgas, from which fuel gas is obtained, before the CO conversion reaction,in order to keep the outlay in terms of maintenance resulting fromdeposits and damage to plant components low, to ensure high availabilityof the plant and also to comply with the environmental regulationsregarding the dust content of gases released into the environment. Thededusting can take place in wet or dry form. The advantage of drydedusting is that the heat content can be used for the purpose ofcarrying out the CO conversion reaction at the required temperature. Theoutlet temperature of top gas from a reduction unit is typically in therange of 250-500° C. For optimum temperature control for the subsequentprocess steps, it may be necessary to adjust the temperature a bit moreby cooling, heating or evaporation of water. The heat content isadvantageously used to produce steam, which is needed in order to carryout the CO conversion reaction. It is also advantageous if the steamneeded in order to carry out the CO conversion reaction is obtained atother stations of the process according to various embodiments.

In the event of wet dedusting, it may be necessary for the top gas flowto be heated before the CO conversion reaction is carried out, in orderto ensure that the temperature of the gas flow required for the COconversion reaction is obtained.

The dedusting can take place in a manner such that all of the top gas isdedusted, and after this dedusting a partial quantity is branched off inorder to obtain fuel gas, or the dedusting can take place after thepartial quantity has been branched off in order to obtain fuel gas.

By way of example, the CO₂ produced during the CO₂ removal can becompressed, condensed and/or sequestered, in order to lower the CO₂emissions of the process which are emitted to the environmentalatmosphere.

According to yet another embodiment, an apparatus for carrying out theprocess, may have a reduction unit for the reduction of metal oxides toform metalized material,

a reformer for carrying out catalytic reformation of a mixture of

-   -   a gas containing carbon dioxide (CO₂) and/or steam (H₂O) with    -   gaseous hydrocarbons,

wherein the reformer is provided with a mixture supply line forsupplying the mixture, and wherein the reformer is provided withburners, which are connected to an oxygen supply line, for providingheat by the combustion of fuel gas, having a drawing-off line fordrawing off combustion off-gas from the reformer, having a reducing gassupply line for hot reducing gas from the reformer into the reductionunit, having a discharge line for discharging top gas from the reductionunit, wherein the burners are connected to the discharge line via aconnection line which branches off from the discharge line, and whereina dedusting apparatus is present at least in the discharge line betweenthe reduction unit and the connection line which branches off from it,or in the connection line, characterized in that a CO conversionreactor, a gas cooling apparatus and a CO₂ removal apparatus are presentin succession, as seen from the discharge line, in the connection line,between the dedusting device which may be present and the burners.

The gaseous hydrocarbons are typically natural gas, methane or propane.

According to one embodiment, a hydrocarbon feed line for gaseoushydrocarbons issues into the connection line, as a result of which it ispossible, if required, to admix gaseous hydrocarbons, in order to obtaina fuel gas with the desired calorific value.

In this case, the hydrocarbon feed line for gaseous hydrocarbons canissue into the connection line downstream from the CO₂ removalapparatus, as seen from the discharge line.

According to one embodiment, the dedusting apparatus is a dry-dedustingapparatus, for example a cyclone, a hot-gas filter or a bag filter.

According to another embodiment, the dedusting apparatus is awet-dedusting apparatus.

It is also possible for more than one dedusting apparatus to be present.These can be arranged, for example, both in the discharge line betweenthe reduction unit and the connection line which branches off from itand in the connection line.

According to one embodiment, in this case, by way of example, awet-dedusting apparatus is arranged in the discharge line between thereduction unit and the connection line which branches off from it, and adry-dedusting apparatus is arranged in the connection line.

In this case, a gas heating apparatus is preferably present in theconnection line between the wet-dedusting apparatus and the COconversion reactor.

In FIG. 1, metal oxides 3—in the present case iron oxides—are added to areduction unit 1, here a fixed-bed reduction shaft, via the oxideaddition apparatus 2, for example as pellets or lump ore. The top gas,which is produced from the reducing gas in the reduction unit during thereduction of the metal oxides to form metalized material, is dischargedfrom the reduction unit via the discharge line 5. Compressors 17 a, 17 bare present in the discharge line 5 in order to overcome the pressuredrop which occurs in the plant. A mixture of top gas and gaseoushydrocarbons, in this case natural gas, is supplied via a mixture supplyline 6 into a reformer 4 for the catalytic reformation of a mixture oftop gas and gaseous hydrocarbons. Here, the natural gas is supplied viathe natural gas line 7. The reformer 4 is provided with burners 8 a, 8b, 8 c for providing heat required for the reformation by the combustionof fuel gas. The hot reducing gas formed in the reformer 4 is suppliedto the reduction unit 1 via the reducing gas supply line 9. Thecombustion off-gas is drawn off from the reformer via a drawing-off line10 for drawing off the combustion off-gas produced during the combustionof fuel gas in the reformer. In the process, the combustion off-gasflows out of the reformer 4.

The drawing-off line 10 comprises an apparatus 11 for cooling thecombustion off-gas and for removing water from the combustion off-gas.Cooling and removal of water take place in the same apparatus. Thedrawing-off line 10 leads into a chimney, through which the combustionoff-gas can be released into the environment.

Steam, which can be used for the CO conversion, can also be produced bythe apparatus 11 or by further process waste heat, for example from topgas or the conversion gas after the CO conversion.

The burners 8 a, 8 b, 8 c are provided with apparatuses for supplyingfuel gas, represented by the connection line 12 which branches off fromthe discharge line 5. Fuel gas is fed to the burners 8 a, 8 b, 8 cthrough the connection line 12.

The oxygen required for the combustion of the fuel gas is supplied tothe burners 8 a, 8 b, 8 c via the oxygen supply line 13 for supplyingoxygen—in this case by means of the supply of air. The air is fed intothe oxygen supply line by means of a blower 14.

The drawing-off line 10 is provided with an apparatus for heating theair guided in the oxygen supply line 13, in this case a recuperator 15for indirect heat exchange between the air in the oxygen supply line 13and the combustion off-gas in the drawing-off line 10.

Furthermore, the drawing-off line 10 is provided with an apparatus forheating the mixture of top gas and gaseous hydrocarbons in the mixturesupply line 6, in this case a recuperator 16 for indirect heat exchangebetween the mixture of top gas and gaseous hydrocarbons in the mixturesupply line 6 and the combustion off-gas in the drawing-off line 10.

A dedusting apparatus 18, in this case a wet-dedusting apparatus, ispresent in the discharge line 5 between the reduction unit 1 and thepoint at which the connection line 12 branches off.

A gas heating apparatus 19, in this case a recuperator for indirect heatexchange, a CO conversion reactor 20, a gas cooling apparatus 21 and aCO₂ removal apparatus 22 are present in succession in the connectionline 12, as seen from the point at which the latter branches off fromthe discharge line 5.

Here, a steam supply line 23 issues into the connection line 12 upstreamfrom the CO conversion reactor 20, as seen from the point at which saidconnection line branches off from the discharge line 5.

The discharge of steam which has been produced from the CO conversionreactor 20 is indicated by a dashed arrow which proceeds from thelatter. The discharge of condensate from the gas cooling apparatus 21 isindicated by an arrow which proceeds from the latter. The discharge of aCO₂-rich gas flow from the CO₂ removal apparatus 22 is indicated by adashed arrow which proceeds from the latter. By way of example, theCO₂-rich gas flow can be sequestered.

A hydrocarbon feed line 24 for gaseous hydrocarbons issues into theconnection line 12 downstream from the CO₂ removal apparatus 22, as seenfrom the discharge line.

As indicated by an arrow, the metal oxides 3 reduced in the reductionunit 1 are removed from the reduction unit 1.

The top gas produced during the reduction is discharged out of thereduction unit through the discharge line 5. After dedusting in thededusting apparatus 18, a partial quantity of the top gas is guided inthe connection line 12 to the burners 8 a, 8 b, 8 c, said top gasfirstly being heated in the gas heating apparatus 19 to a temperaturerequired for the CO conversion reactor 20 to function and, after steamhas been supplied via the steam supply line 23, being subjected to theCO conversion reaction in the CO conversion reactor 20. The productobtained in the process, referred to as conversion gas, is cooled in thegas cooling apparatus 21 and steam carried along is removed therefrom bycondensation, and CO₂ is then removed therefrom in the CO₂ removalapparatus 22. The CO₂-depleted product of this step, referred to asCO₂-depleted conversion gas, is used as fuel gas in the burners 8a, 8 b,8 c after gaseous hydrocarbons have been admixed through the hydrocarbonfeed line 24. The oxygen required for combustion is supplied via theoxygen supply line 13 in the form of air compressed by means of theblower 14.

Hot reducing gas is produced in the reformer 4 by reforming a mixture oftop gas and gaseous hydrocarbons, and is fed to the reduction unit viathe reducing gas supply line 9.

FIG. 2 shows an apparatus analogous to FIG. 1, with the difference thatthere is no dedusting apparatus 18 and no gas heating apparatus 19.Instead,

-   -   there is a dedusting apparatus 25 in the form of a wet-dedusting        apparatus in the discharge line 5 downstream from the point at        which the connection line 12 branches off, as seen from the        reduction unit 1, and    -   there is a dedusting apparatus 26 in the form of a dry-dedusting        apparatus in the connection line 12 between the point at which        the connection line 12 branches off from the discharge line 5        and the CO conversion reactor 20.

Since no temperature loss occurs in the dedusting apparatus 26, no gasheating apparatus 19 is needed to ensure that the temperature requiredfor the CO conversion reactor is obtained. For greater clarity, only theapparatus parts which appear in addition in FIG. 2 compared to FIG. 1are provided with reference symbols.

FIG. 3 shows an apparatus analogous to FIG. 1, with the difference thatthere is no dedusting apparatus 18 and no gas heating apparatus 19.

Instead,

-   -   there is a dedusting apparatus 27 in the form of a dry-dedusting        apparatus in the discharge line 5 upstream from the point at        which the connection line 12 branches off, as seen from the        reduction unit 1, and    -   there is an apparatus for cooling the top gas, which comprises        the cooling element 28 designed as a recuperator and the gas        cooler 30 operated with cooling water 29, in the discharge line        5 downstream from the point at which the connection line 12        branches off, as seen from the reduction unit 1.

Since no temperature loss occurs in the dedusting apparatus 27, no gasheating apparatus 19 is needed to ensure that the temperature requiredfor the CO conversion reactor is obtained. For greater clarity, only theapparatus parts which appear in addition in FIG. 3 compared to FIG. 1are provided with reference symbols.

FIG. 4 shows an apparatus analogous to FIG. 2, with the difference thatsyngas from a coal gasification process containing up to 40% by volumecarbon dioxide and up to 55% by volume steam is used instead of top gasas the gas containing carbon dioxide (CO₂) and/or steam (H₂O). Thissyngas from a coal gasification process (not shown) is fed into themixture supply line 6 via the syngas line 31 which issues into themixture supply line 6. The mixture of syngas and natural gas therebygenerated in the mixture supply line 6 is reformed in the reformer 4.For greater clarity, only the apparatus parts which appear in additionin FIG. 4 compared to FIG. 2 and the natural gas line 7 are providedwith reference symbols.

LIST OF REFERENCE SYMBOLS

1 Reduction unit

2 Oxide addition apparatus

3 Metal oxides

4 Reformer

5 Discharge line

6 Mixture supply line

7 Natural gas line

8 a, 8 b, 8 c Burners

9 Reducing gas supply line

10 Drawing-off line

11 Apparatus for cooling/removing H₂O

12 Connection line

13 Oxygen supply line

14 Blower

15 Recuperator

16 Recuperator

17 a, 17 b Compressors

18 Dedusting apparatus

19 Gas heating apparatus

20 CO conversion reactor

21 Gas cooling apparatus

22 CO₂ removal apparatus

23 Steam supply line

24 Natural gas feed line

25 Dedusting apparatus

26 Dedusting apparatus

27 Dedusting apparatus

28 Cooling element

29 Cooling water

30 Gas cooler

31 Syngas line

1. A process for the reduction of metal oxides to form metalizedmaterial by contact with hot reducing gas, wherein the reducing gas isproduced at least partially by catalytic reformation of a mixture of agas containing at least one of carbon dioxide and steam with gaseoushydrocarbons, the process comprising: providing the heat for theendothermal reformation processes which take place during thereformation at least partially by the combustion of a fuel gas, anddrawing off the combustion off-gas produced in the process, wherein thefuel gas is obtained at least partially from a partial quantity of thetop gas produced during the reduction of metal oxides to form metalizedmaterial, wherein the partial quantity of the top gas, from which thefuel gas is obtained, is firstly subjected to dedusting and then to a COconversion reaction, and the conversion gas obtained during the COconversion reaction is subjected to CO₂ removal after cooling, and theCO₂-depleted conversion gas produced in the process is used at least asa component of the fuel gas.
 2. The process according to claim 1,wherein—the gas containing at least one of carbon dioxide and steam istop gas from the process for the reduction of metal oxides.
 3. Theprocess according to claim 1, wherein the gas containing at least one ofcarbon dioxide and steam is export gas from a smelting reduction processor syngas from a coal gasification process.
 4. The process according toclaim 1, wherein gaseous hydrocarbons are admixed to the CO₂-depletedconversion gas in order to obtain fuel gas.
 5. The process according toclaim 1, wherein the dedusting takes place in dry form.
 6. The processaccording to claim 1, wherein the dedusting takes place in wet form. 7.An apparatus comprising a reduction unit for the reduction of metaloxides to form metalized material, a reformer for carrying out catalyticreformation of a mixture of a gas containing at least one of carbondioxide and steam with gaseous hydrocarbons, wherein the reformer isprovided with a mixture supply line for supplying the mixture, andwherein the reformer is provided with burners, which are connected to anoxygen supply line, for providing heat by the combustion of fuel gas,having a drawing-off line for drawing off combustion off-gas from thereformer, having a reducing gas supply line for hot reducing gas fromthe reformer into the reduction unit, having a discharge line fordischarging top gas from the reduction unit, wherein the burners areconnected to the discharge line via a connection line which branches offfrom the discharge line, and wherein a dedusting apparatus is present atleast in the discharge line between the reduction unit and theconnection line which branches off from it, or in the connection line,and wherein a CO conversion reactor, a gas cooling apparatus and a CO₂removal apparatus are present in succession, as seen from the dischargeline, in the connection line, between the dedusting device which may bepresent and the burners.
 8. The apparatus according to claim 7, whereina hydrocarbon feed line for gaseous hydrocarbons issues into theconnection line.
 9. The apparatus according to claim 8, wherein thehydrocarbon feed line for gaseous hydrocarbons issues into theconnection line downstream from the CO₂ removal apparatus, as seen fromthe discharge line.
 10. The apparatus according to claim 7, wherein thededusting apparatus is a dry-dedusting apparatus.
 11. The apparatusaccording to claim 7, wherein the dedusting apparatus is a wet-dedustingapparatus.
 12. The apparatus according to claim 11, wherein a gasheating apparatus is present in the connection line between thewet-dedusting apparatus and the CO conversion reactor.
 13. The apparatusaccording to claim 7, wherein the reduction unit is a fluidized bedcascade.
 14. The apparatus according to claim 7, wherein the reductionunit is a fixed-bed reduction shaft.
 15. A system for the reduction ofmetal oxides to form metalized material by contact with hot reducinggas, wherein the reducing gas is produced at least partially bycatalytic reformation of a mixture of gas containing at least one ofcarbon dioxide and steam with gaseous hydrocarbons, the systemcomprising: means for providing the heat for the endothermal reformationprocesses which take place during the reformation at least partially bythe combustion of a fuel gas, and means for drawing off the combustionoff-gas produced in the process, wherein the system is configured toobtain fuel gas at least partially from a partial quantity of the topgas produced during the reduction of metal oxides to form metalizedmaterial, wherein the system is further configured to subject thepartial quantity of the top gas, from which the fuel gas is obtained,firstly to dedusting and then to a CO conversion reaction, and tosubject the conversion gas obtained during the CO conversion reaction toCO₂ removal after cooling, and to use the CO₂-depleted conversion gasproduced in the process at least as a component of the fuel gas.
 16. Thesystem according to claim 15, wherein the gas containing at least one ofcarbon dioxide and steam is top gas from the process for the reductionof metal oxides.
 17. The system according to claim 15, wherein the gascontaining at least one of carbon dioxide and steam is export gas from asmelting reduction process or syngas from a coal gasification process.18. The system according to claim 15, wherein gaseous hydrocarbons areadmixed to the CO₂-depleted conversion gas in order to obtain fuel gas.19. The system according to claim 15, wherein the dedusting takes placein dry form.
 20. The system according to claim 15, wherein the dedustingtakes place in wet form.